A couple of years ago the house my sister was living in became something of a problem.
They would hear footsteps from the floor above, when they knew that no one was up there; They would see shadowy forms out of the corner of their eyes; And they would constantly have the strong feeling of dread, no matter what room of the house they were in.
This creepy feeling actually increased over time as the happenings became much more frequent and much more ominous. Ghostly knocking and voices became the norm; literally it was a daily occurrence. The shadows became more defined and would literally sit in dark corners and watch a rooms occupants for extended periods of time. They began to avoid parts of the house where activity seemed to pick up in intensity when they were in it.
Then there were two very strange and terrifying occurrences really shook us up.
The first happened to my brother one night when he went to stay. He decided to sleep on their couch instead of a guest room, since the living room had become something of a hotspot in recent times. He awoke suddenly in the middle of the night and became aware of a black figure in the room that was darker than the night around it. It paces the room soundlessly for a short period of time, then it seemed to crawl up a wall and melt into the ceiling above. The area, when he examined it in the morning, was approximately where our sisters room was, one floor above.
The second happened a few weeks later. My sister was asleep in her bed when she felt the mattress shift and sink, as if someone had sat down beside her. She sat up and began to say the Lord's prayer while she reached for a small bottle of holy water she had purchased. She daubed the 4 corners of the bed and commanded the spirit to leave her in peace. What happened next terrified her so much she called both my brother and I in the middle of the night.
As she commanded the spirit to depart, she suddenly heard a growl that chilled her blood. Then the bed began to shake violently while the growling continued. This lasted for about 30 seconds, then ended abruptly. At this point she turned on the lights, called us frantically, and dressed to leave immediately.
She made arrangements to have the house blessed, but it turns out that such things sometimes have to be scheduled several weeks in advance (much to my surprise). During the waiting period, a local ghost hunting group heard about the house and asked to do an investigation. Seeing as how she didn't have any other means of addressing the problem, she agreed.
The group did a 6 hour walk through investigation, followed by another 6 where the recorders and cameras were left to run in the empty house. While they caught nothing on video and still cameras, the audio was described to me as "One of the most chilling 12 hours of audio they'd ever experienced". They tallied no fewer than 5 different voices speaking during the entire length, the majority being female. There were a lot of unknown noises that they could not figure out a source, mainly in the vein of things being moved or bangs and crashes. The final voice was what they pegged as "male" but even the lead investigator said he had never heard such a deep and terrifying male voice. While some of the female voices could be understood, the male voice was unintelligible and consisted of raspy words and growls. The final nail in the proverbial coffin on the audio occurred during the part where no one was in the house. At some time around 4 in the morning, madness seemed to have broken out in the place. For a stretch of about 10 minutes, two separate audio recorders captured what I will describe as a temper tantrum. The stretch began with the voices talking to each other in an agitated state. Then you hear LOUD footsteps going up the stairs, followed by a series of booms and crashes, as if someone was taking the house apart looking for something. Then it goes quiet for a moment, then the female voices begin to murmur to each other. Suddenly there is a large explosion of sound as whatever went up the stairs comes back down, even louder than before. The female voices totally cease and a very distinct growling can be heard. Then there is a very loud crash, which seemed to have been the table where the recorder was placed, since you can head the recorder bouncing on the wood. Then the sequence ends with the basement door being opened violently, and what sounds like something scuttling down the stairs. Not human footsteps, but something going on more than two legs. Then everything stopped, and the house is silent until the team returns and turns off the equipment.
Needless to say, my sister went to her church and told them about this. The house blessing/cleansing was done within days. Long story short, they had to do it twice, as the priest said he still felt the presence fighting back as he was blessing the house during round one. The second time seemed effective, and the house was quiet for a couple of months. Then the process began again. This time my sister opted to move out instead of going through the whole thing again. She also suspected that a room mate might have been dabbling in something dark, and might have been actively calling it back.